Electronic ignition systems for an internal combustion engine

摘要

A device for automatically varying the ignition spark advance angle in an electronically controlled ignition system for an internal combustion engine, in which there is a first sensor for producing a train of pulses the pulse repetition frequency of which represents the engine speed and a second sensor for producing a single pulse once each revolution of the engine when the crankshaft is at the top dead center position. A pulse counter counts the pulses from the first sensor and acts to discharge the ignition spark when it reaches a predetermined count: this counter is reset to zero each cycle by the pulse from the second sensor, there is also a timing device which sets a predetermined time interval in advance of the top dead center position and means for doubling the frequency of the pulses counted by the said counter for varying the rate at which the spark advance angle varies with change in speed of the engine, depending on whether the engine speed is above or below a threshold speed determined by the timing interval of the said timing circuit.